This invention relates generally to apparatus for coupling electrical conductors and more specifically to a connector especially adapted for the electrical coupling of high current capacity conductors subject to varying thermal and mechanical stresses.
The coupling of electrical conductors, especially copper bars or large contact surface terminal connectors for cables, or the like, which carry very high currents presents certain problems. A voltage drop at the interface between conductors generates heat which produces problems other than the obvious loss of efficiency. For example, the thermal expansion of the heated conductors not only subjects the conductor terminals themselves to deformation, but also may subject the clamping or connecting device to distortion. A change to a lower temperature, by cooling or ceasing the flow of current, will cause the conductors and/or the connecting structure to contract; thereby changing the actual conducting surface contact. When two conductors are placed together along conducting surfaces, it is virtually impossible to obtain more than a few points of contact between the two conducting surfaces due to irregularities which inevitably exist, regardless how well the two conducting surfaces are clamped together. The currents are concentrated at the points of contact and the heat generated by the current flow is also concentrated at the points of contact; thereby subjecting the terminals to uneven rates of thermal expansion which magnifies the problem referred to above. Referring to a more specific electrical connection problem for which this invention was conceived, it is necessary to provide an electrical connector for rather larger high current capacity conductors in a toroidal nuclear fusion test reactor, the ORMAK F/BX. In the reactor, the toroid is made up of four quadrant subassembly sections which require a considerable number of connections of winding segments at the four quadrant joints. The coil terminals to be joined are flat water-cooled copper conductors designed to carry approximately 300,000 amperes. The specified contact pressure between terminals and connector is 2000 psi. In addition to these requirements, the connections between sections must be made by a remote controlled machine. A further condition is that the connector be constructed from nonmagnetic parts since the coils are subjected to extremely high magnetic fields.